I purchased a 3point hitch cone spreader (I can’t remember the brand name) that has two controllable outlet doors that allow granular material to be dropped on either side of the spinner and therefore more concentrated applications on the preferred side. It has a poly cone, so is less prone to corrosion. It is very light and easy to hitch/unhitch from the tractors we use it on. The only drawback I’ve found is the decal and owners manual have units of measurement that do not convert well to pounds and/or acres. I purchased it at United Ag and Turf in South Royalton and their phone number is 802-763-8082 of you’d like to call them for more information.
Do you have any opportunity to use a water soluble product and apply them through a sprayer? That would be more accurate and precisely target the desired soil area. We have also had very good results applying fertilizer through our drip irrigation system too.
I use a cone spreader and it does a good job. We have a Kabota 2030 so not a sub compact but still a relatively small tractor. It takes some finessing at first with how much you open the chute, speed of tractor, etc but after a while it works out. I can let you know when I’m spreading stuff if you want to see it firsthand. Haven’t gotten my stuff yet though so it’ll be a couple weeks although I wish I had it already. Hard to get deliveries to this area - they always wait for another order nearby to combine it with.